[gdb/testsuite/ada] Fix number-of-bp test in bp_inlined_func.exp

[gdb/testsuite/ada] Fix number-of-bp test in bp_inlined_func.exp

At the moment, bp_inlined_func.exp passes for a combined current gcc and
gdb-binutils repos build but fails for a build with system gcc (7.3.1) and
ld (2.29.1).

It checks for 4 breakpoints on read_small:
...
gdb_test "break read_small" \
         "Breakpoint $decimal at $hex: read_small\\. \\(4 locations\\)" \
         "set breakpoint at read_small"
...
and fails because it gets 5 breakpoint locations instead:
...
(gdb) break read_small
Breakpoint 2 at 0x401f9a: read_small. (5 locations)
(gdb) FAIL: gdb.ada/bp_inlined_func.exp: set breakpoint at read_small
...

The 4 expected breakpoint locations are inlined versions of read_small, and
the 5th breakpoint location has this address:
...
(gdb) info breakpoint
Num     Type           Disp Enb Address            What
1       breakpoint     keep y   <MULTIPLE>
1.1                         y     0x0000000000401f9a in b.read_small
                                                   at bp_inlined_func/b.adb:20
...
which is the read_small function itself:
...
(gdb) x 0x0000000000401f9a
0x401f9a <b__read_small+4>:     0x22f8058b
...

This patch updates the test to allow 5 breakpoint locations.

Tested on the configurations mentioned above, on x86_64.

2018-06-18  Tom de Vries  <tdevries@suse.de>

	* gdb.ada/bp_inlined_func.exp: Allow 5 breakpoint locations.